Long-term objectives of the proposed work are to find out what new pathogenic mechanisms are involved in initiation and progression of idiopathic lung fibrosis (IPF) with the intention to discover new molecular targets that can be used as therapeutic tools. As the name suggests, IPF is a disorder with an enigmatic pathogenesis. Even if many investigators have emphasized intraalveolar inflammation as a cause of IPF, anti-inflammatory and immune-modulator therapies have proved to be only minimal effective in limiting the illnesses and in modifying the natural course of the disease. Currently it is assumed that IPF is an epithelial- fibroblastic disease caused by unidentified endogenous or environmental stimuli that disrupt the normal alveolar epithelial cells homeostasis (the onset), followed-on by the diffuse activation of the alveolar epithelium (as a gateway for progression) and finally by aberrant epithelial repair. An outcome of activated alveolar epithelium is the production of potent fibrogenic molecules as tissue factor and plasminogen activator inhibitors that may generate an anti-fibrinolytic intraalveolar environment that facilitate an increased fibrotic response, and cytokines such as tumor necrosis factor and transforming factor ? (TGF?). It was shown that the levels of caveolin 1 (cav-1) are decreased in type I epithelial cells after radiation-induced lung injury, as well as in a model of bleomicin induced pulmonary fibrosis. More than that, the cav-1 knockout mice develop lung fibrosis and may be a reliable model for studying IPF. My long-term goals are to study the pathways and the molecular mechanisms by which the caveolins are involved in IPF. The present application will study the distribution of cav-2 and TGF?-receptor (TGF?-R) throughout the lung, will identify the existing spatiotemporal relations between them and will examine the molecular interactions between cav-2 and the TGF? signaling pathways with a focus on Smads and the turnover of TGF?-R. To this intent I will use human lung tissue provided by LTRC to find out the differences between the distribution of TGF?-R and cav-2 in healthy lung tissue versus lungs with IPF, and I will isolate human lung fibroblasts to create a model (fibroblasts with low levels of cav-2) that will allow separating the contribution of cav-2, to the pathogenesis of IPF, from what was reported to be a cav-1 deficiency effect. The data generated by this application will broaden the knowledge related to the pathogenic mechanisms involved in IPF and will provide new information needed to better understand the participation of caveolins in pulmonary diseases. In order to achieve our goals we are proposing the following: i) #1 To investigate the expression and to determine the subcellular localization of TGF?-R and Smads in relation to cav-2 from lung specimens of IPF patients, and ii) #2 To investigate the functional consequences of cav-2 deficiency on TGF? signaling and extracellular matrix production in lung specimens of IPF patients. PUBLIC HEALTH RELEVANCE: The aim of this proposal is to understand how the proteins caveolins (structural proteins recognized for their ability to glue together different molecules) are involved in the beginning and progression of Idiopathic Pulmonary Fibrosis (IPF). IPF is a distinct and specific form of chronic lung disease of unknown cause, limited to the lungs, and characterized by cellular proliferation (especially the fibroblast) and accumulation of extracellular material (mostly collagen like), that finally leads to irreversible destruction of lung architecture. The lack of knowledge of the mechanisms involved, along with the failure of all therapies used to date, are good reasons for more research oriented toward sorting out the factors involved and for finding new therapies that work. Recent work found out that in patients with IPF the levels of caveolins are lower and pointed to their involvement in starting the disease. The reduction in caveolin levels reported in IPF patients could be corrected by using cell penetrating fragments of caveolins (described first by Lisanti's group for caveolin-1) as therapeutic agents, which could represent a new class of drugs for the treatment of the disease. However, the usage of caveolin-based drugs awaits a clear delineation of the role that caveolins play in the development of the disease. Thus, we are putting forward this proposal aimed to explore the role of the caveolins and their interrelations with another important molecule for the development and progression of the disease, the transforming growth factor in the initiation and progression of IPF. Therefore nothing could be more important, for the public health than the understanding of the causes of such a devastating disease that will allow the development of real therapies able to control and may be to reverse it. (End of Abstract)